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Abstract:

Test apparatus (30) and method (70) for testing a turbocharger (20)
having a turbine (20T) that operates a compressor (20C). A compressed air
source (32) operates the turbine; and a device (42) creates back-pressure
at an outlet (20CO) of the compressor.

Claims:

1. Test apparatus for testing a turbocharger having a turbine that
operates a compressor, the apparatus comprising: a compressed air source
for operating the turbine; and a device for creating back-pressure at an
outlet of the compressor.

2. Test apparatus as set forth in claim 1 further comprising a supply
pressure control loop for setting air pressure at an inlet of the turbine
to which the compressed air source supplies air.

3. Test apparatus as set forth in claim 2 in which the supply pressure
control loop comprises a pressure transducer for measuring air pressure
at the inlet of the turbine, a supply pressure control valve for
controlling air pressure at the inlet of the turbine, and a supply
pressure control valve controller for controlling the supply pressure
control valve to cause air pressure measured by the pressure transducer
to correspond to a specified air pressure.

4. Test apparatus as set forth in claim 1 further comprising a supply
flow control loop for setting massflow rate of air entering the inlet of
the turbine.

5. Test apparatus as set forth in claim 4 in which the supply flow
control loop comprises a massflow meter for measuring massflow rate of
air entering the inlet of the turbine, a supply flow control valve for
controlling massflow rate of air entering the inlet of the turbine, and a
supply flow control valve controller for controlling the supply flow
control valve to cause massflow rate of air measured by the massflow
meter to correspond to a specified massflow rate.

6. Test apparatus as set forth in claim 1 further comprising a supply
pressure control loop for setting air pressure at an inlet of the turbine
to which the compressed air source supplies air and a supply flow control
loop for setting massflow rate of air entering the inlet of the turbine.

7. Test apparatus as set forth in claim 1 in which the device for
creating back-pressure at an outlet of the compressor comprises a
compressor back-pressure control valve.

8. Test apparatus as set forth in claim 7 further comprising a compressor
back-pressure control loop comprising a compressor outlet pressure
transducer for measuring pressure at the outlet of the compressor and a
compressor back-pressure control valve controller for controlling the
compressor back-pressure control valve to cause air pressure measured by
the compressor outlet pressure transducer to correspond to a specified
back-pressure.

9. Test apparatus as set forth in claim 8 further comprising a compressor
outlet massflow meter for measuring massflow rate of air leaving the
compressor outlet.

10. Test apparatus as set forth in claim 9 further comprising a
compressor supply pressure transducer for measuring pressure at an inlet
of the compressor.

11. Test apparatus as set forth in claim 9 further comprising an air
exhaust muffler through which that has passed through the compressor and
the compressor outlet back-pressure control valve passes to atmosphere.

12. Test apparatus as set forth in claim 1 further comprising an air
exhaust muffler through which air that has passed through the turbine
passes to atmosphere.

13. A method for testing a turbocharger having a turbine that operates a
compressor, the method comprising: using a compressed air source to
operate the turbine; and with the turbine operating the compressor,
creating back-pressure at an outlet of the compressor by using a device
connected to the compressor outlet to restrict flow coming from the
compressor outlet.

14. A method as set forth in claim 13 further comprising using a supply
pressure control loop to set air pressure at an inlet of the turbine to
which the compressed air source supplies air.

15. A method as set forth in claim 14 further comprising using a pressure
transducer to measure air pressure at the inlet of the turbine, and
controlling a supply pressure control valve to cause air pressure
measured by the pressure transducer to correspond to a specified air
pressure.

16. A method as set forth in claim 13 further comprising using a supply
flow control loop to set massflow rate of air entering the inlet of the
turbine.

17. A method as set forth in claim 16 further comprising using a massflow
meter to measure massflow rate of air entering the inlet of the turbine,
controlling a supply flow control valve through which air enters the
turbine inlet to cause massflow rate of air measured by the massflow
meter to correspond to a specified massflow rate.

18. A method as set forth in claim 13 further comprising using a supply
pressure control loop to set air pressure at an inlet of the turbine to
which the compressed air source supplies air and using a supply flow
control loop to set massflow rate of air entering the inlet of the
turbine.

19. A method as set forth in claim 13 further comprising using a
compressor back-pressure control valve through which air leaving the
outlet of the compressor passes to create back-pressure at the outlet of
the compressor.

20. A method as set forth in claim 19 further comprising using a
compressor outlet pressure transducer to measure pressure at the outlet
of the compressor and using a compressor back-pressure control valve
controller to cause air pressure measured by the compressor outlet
pressure transducer to correspond to a specified back-pressure.

21. A method as set forth in claim 20 further comprising using a
compressor outlet massflow meter to measure massflow rate of air leaving
the compressor outlet.

22. A method as set forth in claim 21 further comprising a compressor
supply pressure transducer for measuring pressure at an inlet of the
compressor.

23. A method as set forth in claim 21 further comprising passing air that
has passed through the compressor through an air exhaust muffler.

24. A method as set forth in claim 13 further comprising passing air that
has passed through the turbine through an air exhaust muffler.

Description:

TECHNICAL FIELD

[0001] This disclosure relates to internal combustion engine
turbochargers, and in particular to pre-installation testing of such
turbochargers.

BACKGROUND

[0002] An internal combustion engine turbocharger comprises a turbine that
is operated by engine exhaust to drive a compressor that creates
superatmospheric pressure, i.e. boost, in an engine intake manifold
through which charge air enters engine cylinders to support combustion of
fuel. A variable geometry turbocharger and a wastegate turbocharger are
two types.

[0003] A turbocharged internal combustion engine that propels a motor
vehicle such as a commercial truck can provide improved fuel economy and
performance.

SUMMARY OF THE DISCLOSURE

[0004] This disclosure relates to an apparatus and a method for testing
newly manufactured turbochargers before they are installed on internal
combustion engines.

[0005] In this way, a turbocharger that is found non-compliant during
testing will not be installed on an engine. This can yield significant
savings in time, cost, and inconvenience that would be associated with
having to remove a non-compliant turbocharger after its installation on
an engine.

[0006] Compressed air is used, instead of hot exhaust gas, to operate the
turbine. Pressures in the range of 0.5-5.0 bar simulate typical operating
pressures in a turbocharger that is installed on an internal combustion
engine. Pressure and massflow rate are varied to simulate different
turbine operating conditions that would occur in such an engine.
Atmospheric air is drawn into the compressor through an air filter.
Back-pressure at the compressor outlet is created by a back-pressure
control valve that is controlled to restrict compressor flow in varying
degrees thereby simulating various engine conditions. The wastegate of a
wastegate type turbocharger is operated in varying degrees. Massflow
rates from the compressor outlet are measured for different operating
conditions and evaluated against specified values indicative of a
compliant turbocharger. The evaluation determines if a turbocharger is or
is not compliant.

[0007] One general aspect of the disclosure relates to test apparatus for
testing a turbocharger having a turbine that operates a compressor. The
apparatus comprises a compressed air source for operating the turbine;
and a device for creating back-pressure at an outlet of the compressor.

[0008] A more specific aspect relates to a supply pressure control loop
for setting air pressure at an inlet of the turbine to which the
compressed air source supplies air. The supply pressure control loop
comprises a pressure transducer for measuring air pressure at the inlet
of the turbine, a supply pressure control valve for controlling air
pressure at the inlet of the turbine, and a supply pressure control valve
controller for controlling the supply pressure control valve to cause air
pressure measured by the pressure transducer to correspond to a specified
air pressure.

[0009] Another more specific aspect relates to a supply flow control loop
for setting massflow rate of air entering the inlet of the turbine. The
supply flow control loop comprises a massflow meter for measuring
massflow rate of air entering the inlet of the turbine, a supply flow
control valve for controlling massflow rate of air entering the inlet of
the turbine, and a supply flow control valve controller for controlling
the supply flow control valve to cause massflow rate of air measured by
the massflow meter to correspond to a specified massflow rate.

[0010] Another more specific aspect relates to a compressor outlet
back-pressure control loop comprising a compressor outlet pressure
transducer for measuring pressure at the outlet of the compressor and a
compressor back-pressure control valve controller for controlling a
compressor back-pressure control valve to cause air pressure measured by
the compressor outlet pressure transducer to correspond to a specified
back-pressure. A compressor outlet massflow meter measures massflow rate
of air leaving the compressor outlet. A compressor supply pressure
transducer measures pressure at an inlet of the compressor.

[0011] Another general aspect of the disclosure relates to a method for
testing a turbocharger having a turbine that operates a compressor. The
method comprises using a compressed air source to operate the turbine;
and with the turbine operating the compressor, creating back-pressure at
an outlet of the compressor by using a device connected to the compressor
outlet to restrict flow coming from the compressor outlet.

[0012] A more specific aspect relates to using a supply pressure control
loop to set air pressure at an inlet of the turbine to which the
compressed air source supplies air, using a pressure transducer to
measure air pressure at the inlet of the turbine, and controlling a
supply pressure control valve to cause air pressure measured by the
pressure transducer to correspond to a specified air pressure.

[0013] Another more specific aspect relates to using a supply flow control
loop to set massflow rate of air entering the inlet of the turbine, using
a massflow meter to measure massflow rate of air entering the inlet of
the turbine, and controlling a supply flow control valve through which
air enters the turbine inlet to cause massflow rate of air measured by
the massflow meter to correspond to a specified massflow rate.

[0014] Another more specific aspect relates to using a compressor
back-pressure control valve through which air leaving the outlet of the
compressor passes to create back-pressure at the outlet of the
compressor, using a compressor outlet pressure transducer to measure
pressure at the outlet of the compressor, and controlling the compressor
back-pressure control valve to cause air pressure measured by the
compressor outlet pressure transducer to correspond to a specified
back-pressure. A compressor outlet massflow meter is used for measuring
massflow rate of air leaving the compressor outlet, and a compressor
supply pressure transducer is used for measuring pressure at an inlet of
the compressor.

[0015] The foregoing summary is accompanied by further detail of the
disclosure presented in the Detailed Description below with reference to
the following drawings that are part of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a general schematic diagram of a waste-gate type
turbocharger installed on a diesel engine.

[0017] FIG. 2 is schematic diagram of apparatus for testing the
turbocharger prior to its installation on the engine.

[0018]FIG. 3 is schematic diagram of a test method performed by the
apparatus of FIG. 2.

DETAILED DESCRIPTION

[0019]FIG. 1 shows a multi-cylinder engine 10 having structural
components assembled together to form engine cylinders within which
combustion of fuel occurs to operate a kinematic mechanism comprising
pistons, connecting rods, and a crankshaft. Fresh air for supporting
combustion of fuel is delivered to cylinders of engine 10 through an
intake system 12 that comprises an intake manifold 14 serving the engine
cylinders.

[0020] Engine 10 further comprises an exhaust system 16 that comprises an
exhaust manifold 18 at which combustion-created exhaust from the engine
cylinders enters the exhaust system for conveyance to a tailpipe through
which the exhaust passes into the surrounding atmosphere.

[0021] A turbocharger 20 comprises a turbine 20T in exhaust system 16 and
a compressor 20C in intake system 12. Engine exhaust leaving exhaust
manifold 18 passes through turbine 20T before continuing through the
remainder of exhaust system 16 to the tailpipe. The exhaust that passes
through turbine 20T operates turbocharger 20.

[0022] Turbine 20T is coupled to compressor 20C by a shaft 20S to cause
compressor 20C to compress air passing through intake system 12, thereby
developing boost for engine 10. Turbocharger 20 is a wastegate type that
comprises a wastegate 20WG. The extent to which wastegate 20WG opens
determines the quantity of air that is shunted away from the turbine
wheel which is the rotating part of turbine 20T that rotates the
compressor wheel of compressor 20C that draws intake air through the
compressor.

[0024] Turbocharger 20 is placed in association with apparatus 30 by
connecting an inlet 20TI of turbine 20T inlet to an outlet 36 of
compressed air source 32, by connecting an outlet 20TO of turbine 20T to
an inlet of an air exhaust muffler 38 whose outlet is open to atmosphere,
by communicating an inlet 20CI of compressor 20C through a fresh air
filter 40 to atmosphere, and by connecting an outlet 20CO of compressor
20C to an inlet of a back-pressure control valve 42 whose outlet is
communicated through an air exhaust muffler 44 to atmosphere. When
compressed air source 32 is operating turbine 20T during a test, the
pressure at turbine inlet 20TI and the massflow rate through turbine 20T
are controlled in accordance with a test sequence of different
combinations of pressure and massflow rate.

[0025] Compressed air source 32 comprises a tank 46 into which air is
compressed by an air compressor (not shown) and a supply pressure control
valve 48 which can vent some air coming from tank 46 through an air
exhaust muffler 50 to atmosphere in order to set a selected magnitude for
pressure of air being supplied through a supply flow control valve 52 and
a massflow meter 54 to turbine inlet 20TI. A supply pressure control loop
56 includes an electronic controller to which a turbine supply pressure
transducer 58 provides a measure of pressure at turbine inlet 20TI.
Supply pressure control loop 56 adjusts supply pressure control valve 48
to set pressure at turbine inlet 20TI to a pressure setting command input
to the loop. Supply pressure control loop 56 provides feedback control
that assures correspondence of actual pressure with the pressure setting
command input.

[0026] Massflow meter 54 provides a measurement of massflow rate of air
passing through turbine 20T to a supply massflow rate control loop 60
which includes an electronic controller for adjusting supply flow control
valve 52 to assure a massflow rate of air passing through turbine 20T
that corresponds to a massflow rate setting command input to the loop.
Collectively, the two control loops 56, 60 set the power input to the
turbine wheel of turbine 20T.

[0027] A compressor supply pressure transducer 62 measures air pressure at
compressor inlet 20CI. A compressor outlet massflow meter 64 measures
massflow rate of air leaving compressor outlet 20CO. Back-pressure at
compressor outlet 20CO is measured by a compressor outlet pressure
transducer 66. That measurement is used by a compressor back-pressure
control loop 68 to adjust back-pressure control valve 42 in order to set
back-pressure at compressor outlet 20CO during testing of turbocharger 20
to a compressor back-pressure setting command input to the loop. In this
way, compressor back-pressure control loop 68 provides feedback control
that assures correspondence of actual back-pressure with the
back-pressure setting command input.

[0028]FIG. 3 shows steps of a method 70 for testing turbocharger 20. A
first step 72 comprises dressing turbocharger 20 in preparation for its
installation in apparatus 30 by a subsequent clamping step 74. The
particular type (or model) of turbocharger (step 76) determines specific
combinations of command input settings that are to be applied to the
turbocharger during its testing.

[0029] With the turbocharger installed in apparatus 30, lubricating oil is
pumped from oil source 34 to lubricate shaft 20S (step 78). Turbine 20T
is then operated with turbine supply pressure by supply pressure control
loop 56 being set to a specified pressure setting command (step 80) and
turbine supply massflow rate being set by supply massflow rate control
loop 60 to a specified massflow rate setting command (step 82). Both
supply pressure and supply massflow rate are allowed to stabilize (step
84).

[0030] Waste gate 20WG is set to a specified position (step 86).
Compressor back-pressure is set by compressor back-pressure control loop
68 to a specified test pressure (step 88), and the massflow rate from
compressor 20C is measured (step 90).

[0031] The sequence of steps 80 through 90 is then repeated (steps 92, 94)
for various combinations of pressure setting command inputs to control
loop 56, massflow rate command inputs to loop 60, positions of waste gate
positions 20WG, and compressor back-pressure setting command inputs to
control loop 68. For each combination, compressor massflow rate is
measured.

[0032] The various measurements of compressor massflow rate taken for
different operational conditions of turbocharger 20 are evaluated against
specified values that define a compliant turbocharger. If the
measurements are within allowed tolerances, the turbocharger is deemed
compliant and suitable for installation on an engine. If the measurements
are not within allowed tolerances, the turbocharger is deemed
non-compliant, allowing it to be repaired or rebuilt for compliance,
before installation on an engine.

[0033] Once the test sequence has been completed (as determined by step
92), pumping of oil to shaft 20S is stopped and the oil lines are purged
(step 96). The turbocharger can then be removed from apparatus 30 (step
98) and undressed (step 100).

Patent applications by Philip James Charles Vince, Columbia, SC US

Patent applications by International Engine Intellectual Property Company LLC